Dengue IgG Antibody, ELISA Serum

Dengue is a mosquito borne disease and it is diagnosed by the isolation of virus, serological tests and/or molecular tests. Dengue serological testing helps to determine if a symptomatic person and/or a person with potential exposure to dengue is infected. The symptoms are non-specific and may mimic other infections like malaria, and hence laboratory tests are essential. Serological tests for the detection of antibodies against dengue are helpful to diagnose the current or recent infection. There are two types of antibodies, i.e IgG and IgM. IgM antibody appear first and tests for the detection of this antibody is most effective when the test is performed 7-10 days after exposure. The levels of IgM increase gradually for few weeks, then gradually decreases and fall below the detectable level. Serum IgM antibodies can be detected from dengue patients as early as three to five days after the onset of fever and generally persist for 30 - 90 days, although detectable levels may be present eight months post-infection. IgG antibodies level appear later at a low titre and slowly increases. In contrast during the secondary infection, IgG antibodies are more compared to IgM and persists for a long term. The diagnosis of dengue infection requires detection of both IgG and IgM as these antibodies are produced in varying levels over the course of illness. Dengue NS1 antigen are early antigen appearing in the blood from the first day after onset of symptoms upto 9th day. Dengue NS1 antigen is a non-structural protein which is indicative of acute phase of dengue infection. Molecular testing used for the detection of Dengue is polymerase chain reaction (PCR). PCR test detects the RNA (the genetic material) of the dengue virus upto 5 days after symptoms appear.

1. Mention the symptoms of dengue?

The common symptoms of dengue fever are high grade fever, severe headache, pain behind the eyes of severe grade, joint, muscle and bone pain, rash on the body and mild bleeding manifestations from nose, gums etc. These symptoms are more common in older children and adults when compared to young children.

Dengue hemorrhagic fever is identified by a fever of 2 to 7 days and general signs and symptoms of dengue fever. When the fever subsides, symptoms like persistent vomiting, severe abdominal pain, and difficulty in breathing etc, may appear. Later the capillaries become leaky and this leads to escape of fluid form the blood vessels in to peritoneum (causing ascitis) and pleural cavity (causing pleural effusion). If uncorrected, this may lead to shock and followed by death.

2. Is dengue fever preventable?

Till date, there is no immunization for dengue fever. Preventing exposure to mosquitoes by using repellents containing DEET and protective clothing can help.

3. Is dengue fever transmitted from person to person?

No it is not transmitted by contact or exposure to respiratory scretions, but by mosquito bite and in rare cases through blood transfusion, organ donation and mother to fetus, the virus can be transmitted.

4. Can a person have a relapse of dengue fever?

Yes, as there are four serotypes of the virus and there is no cross-protective immunity. A subsequent infection usually is associated with a more severe disease.